package com.xs.tool.common.utils;


import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Random;
/*

 外部调用：

 //获取验证码图片和文本(验证码文本会保存在HttpSession中)
 public void getVerifyCodeImage(HttpServletRequest request, HttpServletResponse response) throws IOException {
 //设置页面不缓存
 response.setHeader("Pragma", "no-cache");
 response.setHeader("Cache-Control", "no-cache");
 response.setDateHeader("Expires", 0);
 response.getOutputStream();
 String verifyCode = VerifyCodeImageUtil.generateTextCode(VerifyCodeUtil.TYPE_NUM_UPPER, 4, null);

 //将验证码放到HttpSession里面
 request.getSession().setAttribute("verifyCode", verifyCode);
 log.debug("本次生成的验证码为[" + verifyCode + "],已存放到HttpSession中");

 //设置输出的内容的类型为JPEG图像
 response.setContentType("image/jpeg");
 BufferedImage bufferedImage = VerifyCodeImageUtil.generateImageCode(verifyCode, 90, 30, 3, true, Color.WHITE, Color.BLACK, null);

 //写给浏览器
 ImageIO.write(bufferedImage, "JPEG", response.getOutputStream());
 }

 */

/**
 * 验证码工具类
 */
public class VerifyCodeImageUtil {

  /**
   * 验证码类型为仅数字,即0~9
   */
  public static final int TYPE_NUM_ONLY = 0;

  /**
   * 验证码类型为仅字母,即大小写字母混合
   */
  public static final int TYPE_LETTER_ONLY = 1;

  /**
   * 验证码类型为数字和大小写字母混合
   */
  public static final int TYPE_ALL_MIXED = 2;

  /**
   * 验证码类型为数字和大写字母混合
   */
  public static final int TYPE_NUM_UPPER = 3;

  /**
   * 验证码类型为数字和小写字母混合
   */
  public static final int TYPE_NUM_LOWER = 4;

  /**
   * 验证码类型为仅大写字母
   */
  public static final int TYPE_UPPER_ONLY = 5;

  /**
   * 验证码类型为仅小写字母
   */
  public static final int TYPE_LOWER_ONLY = 6;

  /**
   * 生成随机颜色
   */
  public static Color generateRandomColor() {
    Random random = new Random();
    return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
  }

  /**
   * 生成图片验证码
   *
   * @param type           验证码类型,参见本类的静态属性
   * @param length         验证码字符长度,要求大于0的整数
   * @param excludeString  需排除的特殊字符
   * @param width          图片宽度(注意此宽度若过小,容易造成验证码文本显示不全,如4个字符的文本可使用85到90的宽度)
   * @param height         图片高度
   * @param interLine      图片中干扰线的条数
   * @param randomLocation 每个字符的高低位置是否随机
   * @param backColor      图片颜色,若为null则表示采用随机颜色
   * @param foreColor      字体颜色,若为null则表示采用随机颜色
   * @param lineColor      干扰线颜色,若为null则表示采用随机颜色
   * @return 图片缓存对象
   */
  public static BufferedImage generateImageCode(int type, int length, String excludeString, int width, int height, int interLine, boolean randomLocation, Color backColor, Color foreColor, Color lineColor) {
    String textCode = generateTextCode(type, length, excludeString);
    return generateImageCode(textCode, width, height, interLine, randomLocation, backColor, foreColor, lineColor);
  }

  /**
   * 生成验证码字符串
   *
   * @param type          验证码类型,参见本类的静态属性
   * @param length        验证码长度,要求大于0的整数
   * @param excludeString 需排除的特殊字符（无需排除则为null）
   * @return 验证码字符串
   */
  public static String generateTextCode(int type, int length, String excludeString) {
    if (length <= 0) {
      return "";
    }
    StringBuilder verifyCode = new StringBuilder();
    int i = 0;
    Random random = new Random();
    switch (type) {
      case TYPE_NUM_ONLY:
        while (i < length) {
          int t = random.nextInt(10);
          //排除特殊字符
          if (null == excludeString || !excludeString.contains(t + "")) {
            verifyCode.append(t);
            i++;
          }
        }
        break;
      case TYPE_LETTER_ONLY:
        while (i < length) {
          int t = random.nextInt(123);
          if ((t >= 97 || (t >= 65 && t <= 90)) && (null == excludeString || excludeString.indexOf((char) t) < 0)) {
            verifyCode.append((char) t);
            i++;
          }
        }
        break;
      case TYPE_ALL_MIXED:
        while (i < length) {
          int t = random.nextInt(123);
          if ((t >= 97 || (t >= 65 && t <= 90) || (t >= 48 && t <= 57)) && (null == excludeString || excludeString.indexOf((char) t) < 0)) {
            verifyCode.append((char) t);
            i++;
          }
        }
        break;
      case TYPE_NUM_UPPER:
        while (i < length) {
          int t = random.nextInt(91);
          if ((t >= 65 || (t >= 48 && t <= 57)) && (null == excludeString || excludeString.indexOf((char) t) < 0)) {
            verifyCode.append((char) t);
            i++;
          }
        }
        break;
      case TYPE_NUM_LOWER:
        while (i < length) {
          int t = random.nextInt(123);
          if ((t >= 97 || (t >= 48 && t <= 57)) && (null == excludeString || excludeString.indexOf((char) t) < 0)) {
            verifyCode.append((char) t);
            i++;
          }
        }
        break;
      case TYPE_UPPER_ONLY:
        while (i < length) {
          int t = random.nextInt(91);
          if ((t >= 65) && (null == excludeString || excludeString.indexOf((char) t) < 0)) {
            verifyCode.append((char) t);
            i++;
          }
        }
        break;
      case TYPE_LOWER_ONLY:
        while (i < length) {
          int t = random.nextInt(123);
          if ((t >= 97) && (null == excludeString || excludeString.indexOf((char) t) < 0)) {
            verifyCode.append((char) t);
            i++;
          }
        }
        break;
      default:
        throw new IllegalStateException("Unexpected value: " + type);
    }
    return verifyCode.toString();
  }

  /**
   * 已有验证码,生成验证码图片
   *
   * @param textCode       文本验证码
   * @param width          图片宽度(注意此宽度若过小,容易造成验证码文本显示不全,如4个字符的文本可使用85到90的宽度)
   * @param height         图片高度
   * @param interLine      图片中干扰线的条数
   * @param randomLocation 每个字符的高低位置是否随机
   * @param backColor      图片颜色,若为null则表示采用随机颜色
   * @param foreColor      字体颜色,若为null则表示采用随机颜色
   * @param lineColor      干扰线颜色,若为null则表示采用随机颜色
   * @return 图片缓存对象
   */
  public static BufferedImage generateImageCode(String textCode, int width, int height, int interLine, boolean randomLocation, Color backColor, Color foreColor, Color lineColor) {
    //创建内存图像
    BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    //获取图形上下文
    Graphics graphics = bufferedImage.getGraphics();
    //画背景图
    graphics.setColor(null == backColor ? generateRandomColor() : backColor);
    graphics.fillRect(0, 0, width, height);
    //画干扰线
    Random random = new Random();
    if (interLine > 0) {
      int x = 0, y, y1;
      for (int i = 0; i < interLine; i++) {
        graphics.setColor(null == lineColor ? generateRandomColor() : lineColor);
        y = random.nextInt(height);
        y1 = random.nextInt(height);
        graphics.drawLine(x, y, width, y1);
      }
    }
    //字体大小为图片高度的80%
    int fsize = (int) (height * 0.8);
    int fx = height - fsize;
    int fy = fsize;
    //设定字体
    graphics.setFont(new Font("Default", Font.PLAIN, fsize));
    //写验证码字符
    for (int i = 0; i < textCode.length(); i++) {
      fy = randomLocation ? (int) ((Math.random() * 0.3 + 0.6) * height) : fy;
      graphics.setColor(null == foreColor ? generateRandomColor() : foreColor);
      //将验证码字符显示到图象中
      graphics.drawString(textCode.charAt(i) + "", fx, fy);
      fx += fsize * 0.9;
    }
    graphics.dispose();
    return bufferedImage;
  }
}
